This invention relates generally to weatherstrips for automotive vehicles and specifically to weatherstrips having a core metallic layer and a dissimilar outer appearance metallic layer, separated by a barrier layer.
The worldwide automotive market has become increasing competitive and consumers have become more quality conscious. In particular, Galvanic corrosion has become a significant problem for automotive weatherstrips, and specifically beltline weatherstrips. Within a beltline weatherstrip an aluminum core material is often in contact with an outer aesthetic cap made of stainless steel. Galvanic corrosion can occur since these two metals have a different solution potential wherein the stainless steel acts as a cathode and the aluminum acts as an anode. The electrically conductive solution comes from salt water caused by acid rain, road salt spray and ocean salt spray that seeps between the two metals. This type of galvanic corrosion causes staining, bleeding and often bubbling of rust beneath the synthetic rubber or cap material.
Galvanic corrosion has become more intensified due to the use of EPDM synthetic rubber, rather than the prior SBR type of synthetic rubber previously used. Currently, one method which circumvents the corrosion problem is to use similar materials for the core and for the cap members. However, this usually necessitates that stainless steel be used for both members, thus, the beltline weatherstrip becomes very expensive.
Fender or quarter panel bright strips such as those shown by reference in U.S. Pat. No. 4,709,525, entitled "Molding For Automobile Body Panels, Such As Doors", issued on Dec. 1, 1987 to Adell, and U.S. Pat. No. 4,682,442, entitled "Door Edge Guard And Method", issued on Jul. 28, 1987 to Adell, have used an insulating layer between an inner section of the metal bright strip and the steel body panel. However, these products have not suggested the use of a barrier layer between two inner dissimilar metal parts. Furthermore, these bright strips were not encapsulated within a highly conductive EPDM elastomer. Moreover, the insulating layer used for these parts consists of a polyvinyl chloride (PVC) plastic layer which cannot withstand the high vulcanizing temperatures required for weatherstrips.